Question: Complete the square to solve for $x$. $x^{2}-4x = 0$
Answer: We complete the square by taking half of the coefficient of our $x$ term, squaring it, and adding it to both sides of the equation. Since the coefficient of our $x$ term is $-4$ , half of it would be $-2$ , and squaring it gives us ${4}$ $x^2 - 4x { + 4} = 0 { + 4}$ We can now rewrite the left side of the equation as a squared term. $( x - 2 )^2 = 4$ Take the square root of both sides. $x - 2 = \pm2$ Isolate $x$ to find the solution(s). $x = 2\pm2$ So the solutions are: $x = 4 \text{ or } x = 0$ We already found the completed square: $( x - 2 )^2 = 4$